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Reliable electricity is more than just a technical achievement—it’s a foundation for better lives, economic growth and jobs, and resilient communities. Yet in many developing countries, millions of people still experience frequent blackouts or brownouts, sometimes for several hours each day. Long Duration Energy Storage (LDES)—technologies that can store electricity for 6 hours or more—are emerging as a game-changer, offering the promise of dependable, affordable, and clean energy around the clock. 

Why Does Long-Duration Storage Matter?
Picture entire towns powered by massive batteries—systems capable of storing enough energy to keep hospitals, schools, and industries running for days, not just hours. LDES doesn’t just bridge short gaps; it can absorb surplus energy from solar and wind when production peaks, then deliver reliable electricity through extended periods of low generation—overnight, across cloudy weeks, or during prolonged wind lulls. 

This means that instead of facing routine, multi-hour blackouts, communities could see uninterrupted power even during the longest outages. Imagine a regional hospital continuing critical care through a multi-day storm, or entire industrial zones operating smoothly despite grid instability. For families, LDES means consistent lighting, refrigeration, and connectivity—regardless of weather or time of day. For businesses and industries, it means resilience, growth, and new jobs, as reliable power unlocks investment and productivity. 

In places where outages can stretch for hours or even days, LDES has the potential to shrink these disruptions, dramatically transforming energy access and fueling development at a scale never before possible.

What is LDES?
LDES refers to a suite of energy storage technologies designed to store electricity for much longer than traditional batteries—typically from 6 hours upwards. While short-duration storage helps manage brief fluctuations, LDES enables grids to ride through longer periods of low renewable generation, such as cloudy days or wind lulls, and provides backup during emergencies. This capability is essential for integrating more renewables and ensuring reliable electricity supply in increasingly electrified economies. 

Technologies Driving Innovation: Insights from the LDES Study Tour
While the lithium-ion batteries have accounted for the lion’s share of the newly installed energy storage capacity of both short- and long- duration, the LDES sector is characterized by a remarkable diversity of technologies, each with unique advantages and market applications. The sector is rapidly evolving, with different solutions tailored to specific needs. To accelerate learning and collaboration, the World Bank’s Energy Sector Management Assistance Program (ESMAP), together with IFC and MIGA, hosted an LDES study tour in September 2025.  

The tour brought together 44 experts from 13 countries to explore the latest innovations and market developments in the United States, including site visits in Washington, DC and California’s San Francisco Bay Area. Participants heard expert interventions from ESMAP’s Energy Storage Partnership (ESP) partner the Long Duration Energy Storage Council’s Anna Siefken, and Ted Ko, Founder and Executive Director, Energy Policy Design Institute.  

The program included exchanges with the California Independent System Operator of the wholesale electric grid of California. CAISO has pioneered renewable integration, balancing one of the world’s highest shares of solar and wind while maintaining real-time system reliability. Since 2020, all newly added capacity has been from Variable Renewable Energy and storage. As of August 2025, energy storage capacity reached 14 GW.  

Technologies showcased during the tour included: 

• Thermal Storage: Companies like Rondo Energy, Malta, and Antora Energy are pioneering brick-, molten salt-, and carbon-based thermal storage systems. These solutions convert electricity into heat, which can be stored and later converted back to electricity or used directly for industrial processes.
• Hydrogen and CO Fuel Cells: EnerVenue and the Energy Vault/Calistoga Resiliency Center demonstrated hydrogen-based fuel cell batteries of kW and MW sizes, which offer long-duration backup and are particularly suited for microgrids and resilience applications. Noon Energy is advancing CO-based fuel cell battery technology in pilot scale, targeting island nations.
• Redox Flow Batteries: Invinity has been deploying flow battery technologies at scale, which use liquid electrolytes to store energy and can be scaled for multi-hour or multi-day storage.
• Compressed CO2 Storage: Energy Dome showcased systems that store energy by compressing and releasing carbon dioxide, offering another pathway to long-duration storage. 

These technologies complement established solutions like lithium-ion batteries — which are cost competitive for short-duration storage and have relatively flat costs across durations —pumped hydro, and emerging mechanical systems. Each addresses different market needs, from grid firming and industrial heat replacement to behind-the-meter and microgrid applications. LDES, however, benefits from economies of scale and holds greater cost reduction potential. 

Investment and Financing Challenges
Over $4 billion has been invested in LDES start-ups globally in the past five years, with most funding directed toward manufacturers in developed countries and China. While lithium-ion batteries have dominated early grid-scale deployments, LDES projects are now emerging in minigrids, commercial and industrial applications, and community-level solutions. However, bankability remains a challenge, as most LDES vendors are venture-funded and pre-profitable. Insurance-backed warranties and reference projects—such as those for data centers—are helping to de-risk investments and pave the way for broader adoption. 

Business Models and System Integration
Innovative business models and public-private partnerships are demonstrating the value of LDES in real-world settings. Microgrid projects, such as smart energy bus depots and resiliency centers, show how storage can keep essential services running during outages and emergencies. Flexible ownership models and comprehensive policy frameworks are supporting sustainable market growth across transmission, distribution, and behind-the-meter segments. 

Looking Ahead: The Role of LDES in a Strong Energy Future
The World Bank’s ESMAP, through its Energy Storage Program and the Energy Storage Partnership (ESP), is actively supporting the scale-up and deployment of longer duration energy storage technologies in developing countries where reliable energy access is vital. As LDES technologies mature and costs decline, their ability to deliver long-duration, low-carbon energy will be essential for integrating renewables, strengthening grids, and expanding energy access—especially in regions where outages are common and the need for strong infrastructure is greatest. 

By focusing on the human impact—more dependable power, better services, and new economic opportunities—LDES can help transform lives and communities, making the vision of universal, reliable electricity a reality.